Digital networks have been developed to facilitate the transfer of information, including data and programs, among digital computer systems and other digital devices. A variety of types of networks have been developed and implemented using diverse information transfer methodologies. In some networks, such as the well-known Ethernet, a single wire is used to interconnect all of the devices connected to the network. While this simplifies wiring of the network in a facility and connection of the devices to the network, it results in generally slow information transfer, since the wire can only carry information, in the form of messages, from a single device at a time. To alleviate this to some extent, in some Ethernet installations, the network is divided into a number of sub-networks, each having a separate wire, with interfaces interconnecting the wires. In such installations, wires can carry messages for devices connected thereto simultaneously, which increases the number of messages that can be transferred simultaneously. It is only when a device connected to one wire needs to send a message to a device connected to another wire that wires in two or more sub-networks will be used, making them unavailable for use by other devices connected thereto.
To alleviate this, networks have been developed in which communications are handled through a mesh of switching nodes. The computer systems and other devices are connected to various ones of the switching nodes to, as information sources, provide information for transfer over the network and/or, as destinations, for receiving information from the network, with the information that is transferred being transferred over selected paths of switching nodes comprising the network. In various types of networks, including networks in which information is transferred using the well-known "ATM" ("Asynchronous Transfer Mode") transfer methodology, various information transfer paths through the network between respective sources and destinations can be assigned classes of guaranteed transfer services, such as guaranteed rates at which information can be transferred over the respective paths in the network. A problem arises, however, in that the switching nodes in the network need to be able to efficiently ensure that information to be transferred over the paths with the guaranteed service rates is transferred in accordance with those guaranteed rates, and in addition to provide that they will also be able to transfer information over paths for which no guaranteed service rates are provided.